This invention relates generally to pressure transducers and more particularly concerns a dual capacitance, bonded pressure transducer.
In certain applications, such as in the measurement of either dynamic and static pressures on aircraft, and in aircraft engines, there is a need for a pressure transducer which is physically small but capable of providing accurate results at elevated temperatures, i.e. up to 1,000.degree. F. and higher, without auxiliary cooling devices.
Several types of pressure transducers have been tried in such circumstances, but all have proved unsuccessful, for various reasons. Many such transducers are susceptible to thermal gradients at elevated temperatures, which result in significant shifts in response of the transducer, particularly in the zero point. Other transducers are not capable of measuring both static and dynamic pressures, while still other transducers are too large in size for such applications, or require auxiliary cooling apparatus.
Generally, the capacitance type pressure transducer, since it does not need an auxiliary cooling device, might be expected to come closest to meeting the above specifications, but such transducers have the significant disadvantages of being subject to distortion caused by thermal gradients and are characterized by an output which is nonlinear with respect to change in pressure.
Hence, there are no currently available pressure transducers which provide accurate static and dynamic pressure measurements in an elevated temperature, space restricted environment.
Accordingly, it is a general object of the present invention to provide a pressure transducer which overcomes one or more of the disadvantages of the prior art noted above.
It is another object of the present invention to provide such a pressure transducer which is characterized by an output which is substantially linear with respect to pressure change.
It is a further object of the present invention to provide such a pressure transducer which has a relatively low susceptibility to thermal gradients.
It is another object of the present invention to provide such a pressure transducer which measures both static and dynamic pressure.
It is a still further object of the present invention to provide such a pressure transducer which is relatively small.
It is yet another object of the present invention to provide such a pressure transducer which does not require an auxiliary cooling device.